Titanium metal–organic frameworks (Ti‐MOFs), as an appealing type of artificial photocatalyst, have shown great potential in the field of solar energy conversion due to their well‐studied photoredox activity (similar to TiO2) and good optical responsiveness of linkers, which serve as the antenna to absorb visible‐light. Although much effort has been dedicated to developing Ti‐MOFs with high photocatalytic activity, their solar energy conversion performances are still poor. Herein, we have implemented a covalent‐integration strategy to construct a series of multivariate Ti‐MOF/COF hybrid materials PdTCPP⊂PCN‐415(NH2)/TpPa (composites 1, 2, and 3), featuring excellent visible‐light utilization, a suitable band gap, and high surface area for photocatalytic H2production. Notably, the resulting composites demonstrated remarkably enhanced visible‐light‐driven photocatalytic H2evolution performance, especially for the composite 2 with a maximum H2evolution rate of 13.98 mmol g−1 h−1(turnover frequency (TOF)=227 h−1), which is much higher than that of PdTCPP⊂PCN‐415(NH2) (0.21 mmol g−1 h−1) and TpPa (6.51 mmol g−1 h−1). Our work thereby suggests a new approach to highly efficient photocatalysts for H2evolution and beyond.
Titanium metal–organic frameworks (Ti‐MOFs), as an appealing type of artificial photocatalyst, have shown great potential in the field of solar energy conversion due to their well‐studied photoredox activity (similar to TiO2) and good optical responsiveness of linkers, which serve as the antenna to absorb visible‐light. Although much effort has been dedicated to developing Ti‐MOFs with high photocatalytic activity, their solar energy conversion performances are still poor. Herein, we have implemented a covalent‐integration strategy to construct a series of multivariate Ti‐MOF/COF hybrid materials PdTCPP⊂PCN‐415(NH2)/TpPa (composites 1, 2, and 3), featuring excellent visible‐light utilization, a suitable band gap, and high surface area for photocatalytic H2production. Notably, the resulting composites demonstrated remarkably enhanced visible‐light‐driven photocatalytic H2evolution performance, especially for the composite 2 with a maximum H2evolution rate of 13.98 mmol g−1 h−1(turnover frequency (TOF)=227 h−1), which is much higher than that of PdTCPP⊂PCN‐415(NH2) (0.21 mmol g−1 h−1) and TpPa (6.51 mmol g−1 h−1). Our work thereby suggests a new approach to highly efficient photocatalysts for H2evolution and beyond.
more » « less- Award ID(s):
- 2029800
- NSF-PAR ID:
- 10448025
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 61
- Issue:
- 3
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract It has been rarely reported the morphological control of derivatives of metal‐organic frameworks (MOFs) in hydrothermal conditions for photocatalytic applications. We report here a family of highly efficient composite photocatalysts composed of terephthalic acid/terephthalate (TPA) ligand and TiO2with various morphologies (e. g., nanoparticles, nanosheets, and nanorods). The composites are synthesized by a simple one‐step hydrothermal method in various solvents (i. e., H2O, HF, H2SO4, HCl, and HNO3) using Ti‐based MOF (MIL‐125(Ti)) as precursor. The formation mechanism of composite materials with different morphological features is discussed. Impressively, the composite of TiO2nanoparticles/TPA synthesized using H2O as solvent under hydrothermal condition exhibits the highest photocatalytic H2activity among the studied materials, with a photocatalytic H2production rate of 6.38 mmol g−1 h−1, which is approximately 7.5‐fold higher than pure TiO2(Degussa, P25) and prominent apparent quantum efficiency (AQE) of 65 % at 365 nm. Furthermore, the mechanism of boosted photocatalytic H2production is discussed.
-
more » « less
Abstract Photocatalytic CO2reduction with water to hydrocarbons represents a viable and sustainable process toward greenhouse gas reduction and fuel/chemical production. Development of more efficient catalysts is the key to mitigate the limits in photocatalytic processes. Here, a novel ultrathin‐film photocatalytic light absorber (UFPLA) with TiO2films to design efficient photocatalytic CO2conversion processes is created. The UFPLA structure conquers the intrinsic trade‐off between optical absorption and charge carrier extraction efficiency, that is, a solar absorber should be thick enough to absorb majority of the light allowable by its bandgap but thin enough to allow charge carrier extraction for reactions. The as‐obtained structures significantly improve TiO2photocatalytic activity and selectivity to oxygenated hydrocarbons than the benchmark photocatalyst (Aeroxide P25). Remarkably, UFPLAs with 2‐nm‐thick TiO2films result in hydrocarbon formation rates of 0.967 mmol g−1h−1, corresponding to 1145 times higher activity than Aeroxide P25. This observation is confirmed by femtosecond transient absorption spectroscopic experiments where longer charge carrier lifetimes are recorded for the thinner films. The current work demonstrates a powerful strategy to control light absorption and catalysis in CO2conversion and, therefore, creates new and transformative ways of converting solar energy and greenhouse gas to alcohol fuels/chemicals.
-
more » « less
Abstract A full‐spectrum (300–850 nm) responsive donor–acceptor (D–A) supramolecular photocatalyst tetraphenylporphinesulfonate/fullerene (TPPS/C60) is successfully constructed. The theoretical spectral efficiency of TPPS/C60is as high as 70%, offering the possibility of full‐solar‐spectrum light harvesting. The TPPS/C60performs a highly efficient photocatalytic H2evolution rate of 276.55 µmol h−1(34.57 mmol g−1h−1), surpassing many reported organic photocatalysts. The D–A structure effectively promotes electron transfer from TPPS to C60, which is beneficial to the photocatalytic reaction. Specifically, a giant internal electric field in the D–A structure is built via the enhanced molecular dipole, which dramatically promotes the charge separation (CS) efficiency by 2.35 times. Transient absorption spectra results show a long‐lived CS state TPPS•+–C60•−in the D–A structure, which effectively promotes participation of photogenerated electrons in the reduction reaction. Briefly, this work provides a novel approach for designing high‐performance photocatalytic materials via enhancing the interfacial electric field.
-
Steam reforming of methane (SRM) is one of the most important industrial processes, which produces 95% of hydrogen used in the USA. However, SRM is an endothermic reaction, which requires a high energy input and a high reaction temperature (>800 °C) for the current process. Furthermore, its products must be subjected to a water–gas shift (WGS) process. A photocatalytic process is expected to solve the energy issue and to eliminate the necessity of WGS for SRM. However, the hydrogen yield from the current photocatalytic steam reforming of methane (PSRM) is very low (μmol h −1 g −1 level), which is far below industrial interest. This work demonstrates that a Pt/blackTiO 2 catalyst dispersed on a light-diffuse-reflection-surface is excellent for efficient visible-light PSRM. Under visible light illumination on the catalyst by filtering UV light from AM 1.5G sunlight, CH 4 and H 2 O were directly converted into H 2 and CO 2 without WGS, leading to a high H 2 yield of 185 mmol h −1 g −1 with a quantum efficiency of 60% at 500 °C. The yield is 3 orders of magnitude larger than the reported values, which can be attributed to the synergistic effect between potential and kinetic energies. This opens up a new opportunity for hydrogen production from water and natural gas using solar energy.more » « less
